In-plane electroluminescence from microcavity organic light-emitting transistors

We report the observation of in-plane emission beneath the drain electrode in multilayer heterostructure organic light-emitting transistors (OLETs). A novel modification method for the interface between the hole transport layer and the emission layer has been proposed, which brought a great enhancement for the light power and external quantum efficiency. Further, distributed Bragg reflector was incorporated to the in-plane-emitted OLETs, which combined with the top thin layer of Au, forming a vertical microcavity. The electroluminescence spectra were significantly altered by the microcavity and much narrower linewidth was obtained. The results will help to develop high color purity and white OLETs with high performance, which would be useful for multifunctional displays.     

新型有机非线性光学材料的制备及性能研究

合成了一种新型含呋喃共轭桥的有机二阶非线性光学生色团分子,用IR、1H-NMR和元素分析表征了其结构。热失重分析(TGA)结果表明,化合物的热分解温度为272℃。利用溶致变色法对材料的超极化率μβ值进行了测量,在1 064 nm激光波长下,材料的μgβ值达24 898×10-48esu。将材料作为客体掺杂于聚砜(PSU)中,用旋涂成膜法制成薄膜,对薄膜进行电晕极化后用二次谐波法(SHG)测量其二阶非线性光学系数d33,在激光基频波长为1 064 nm时,测得d33=70 pm/V。     

Synthesis and Electroluminescence properties of Tris [ 5-choloro- 8- hydroxyquinoline] Aluminium Al(5-Clq)3

A new electroluminescent material tris-[5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material Al(5-Clq)₃ in toluene showed absorption maxima at 385 nm which was attributed to the moderate energy (π-π^*) transitions of the aromatic rings. The photoluminescence spectrum of Al(5-Clq)₃ in toluene solution showed a peak at 522 nm. This material shows thermal stability up to 400 ℃. The structure of the device is ITO/0.4 wt%F4-TCNQ doped α-NPD (35 nm) / Al(5-Clq)₃(30 nm)/ BCP (6 nm)/ Alq₃(30 nm)/ LiF (1 nm)/Al(150 nm). This device exhibited a luminescence peak at 585 nm (CIE coordinates, x= 0.39, y= 0.50). The maximum luminescence of the device was 920 Cd/m² at 25 V. The maximum current efficiency of OLED was 0.27 Cd/A at 20 V and maximum power efficiency was 0.04 lm/W at 18 V.     

Photo- and electroluminescence from semiconductor colloidal quantum dots in organic matrices: QD-OLED

The results are reported of an experimental study of samples of organic light-emitting diodes (OLEDs) with luminescent layers fabricated on the basis of two types of CdSe/CdS/ZnS semiconductor quantum dots (QDs) with average CdSe core diameters of 3.2 and 4.1 nm and the same overall diameters of 6.5 nm. The dependences of the LED efficiency on the applied voltage are determined. Assumptions are made about ways of optimizing the design of high-efficiency LEDs.     

A novel high-quality electrochromic material from 3,4-ethylenedioxythiophene bis-substituted fluorene

Poly(2,7-bis (2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-fluorene) (P(EDOT-FE)), a novel electrochromic material obtained from 3,4-ethylenedioxythiophene (EDOT) bis-substituted fluorene (FE) in CH₂Cl₂ solution, and its applications in electrochromic devices (ECD) are discussed. The external EDOT units will not only function as donor groups but also lower the oxidation potential. Fluorescent spectral studies indicate that P(EDOT-FE) with high fluorescence quantum yields and photochemical stability is a novel green-light-emitter. P(EDOT-FE) is switched between brown in the reduced state and blue in the oxidized state. ECD based on P(EDOT-FE) and poly(3,4-ethylenedioxythiophene) (PEDOT) was also fabricated and showed a good electrochromic performance. The ECD constructed by P(EDOT-FE) and PEDOT has good optical contrast (36% at 625 nm), high coloration efficiency (784 cm² C⁻¹), fast response time (0.5 s at 625 nm), better optical memory and long-term stability. Clear change from dark red (neutral) to dark blue color (oxidized) of ECD is demonstrated with robust cycle life. These results provide an avenue for applications of PEDOT family in electrochromic devices.     

一种新型光学装饰材料

主要论述了可作为新型装饰材料的微珠结构的光学定向散射膜片的原理及其实现方法，给出此种装饰材料的制做试验结果。     

Acridine derived stable host material for long lifetime blue phosphorescent organic light-emitting diodes

A host material having acridine as a hole transport moiety, 10-(3′-(9H-carbazol-9-yl)-[1,1′-biphenyl]-3-yl)-9,9-dimethyl-9,10-dihydroacridine (CZBPAC), was explored as the host material of phenylimidazole type Ir triplet emitter to realize both high quantum efficiency and stable operational lifetime. The acridine containing CZBPAC was superior to carbazole based host material with the same backbone structure in that it can improve driving voltage, quantum efficiency and lifetime of the blue phosphorescent organic light-emitting diodes simultaneously.     

8-羟基喹啉铝作为修饰层对C60有机场效应管性能影响的研究

采用真空蒸镀技术制备了以喹啉铝(tris(8-hydroxyquinoline) aluminum, Alq3)作为修饰层的C60有机场效应管器件,并研究了修饰层的厚度对于器件性能的影响。实验表明,随着Alq3修饰层厚度的增加,器件的性能参数得到改进。当Alq3修饰层厚度为10nm时,器件场效应的迁移率达到最大值,为1.2810-2cm2/Vs,阈值电压也下降到了10V。分析了缓冲层使器件性能提高的主要原因可能有两个：一个是可以阻止金属原子扩散进入C60有机层,另一个是使Al/C60界面间的沟道电阻降低。     

Enhanced performance of C60 organic field effect transistors using a tris(8-hydroxyquinoline) aluminum buffer layer

We have investigated the properties of C60-based organic field effect transistors（OFETs） with a tris（8- hydroxyquinoline） aluminum（Alq3） buffer layer inserted between the source/drain electrodes and the active material. The electrical characteristics of OFETs are improved with the insertion of Alq3 film.The peak field effect mobility is increased to 1.28×10^-2 cm²/（V·s） and the threshold voltage is decreased to 10 V when the thickness of the Alq3 is 10 nm.The reason for the improved performance of the devices is probably due to the prevention of metal atoms diffusing into the C60 active layer and the reduction of the channel resistance in Alq3 films.     

Analysis of alternating current driven electroluminescence in organic light emitting diodes: A comparative study

The alternating current (AC) responses of double-injection and double-insulated organic light-emitting diodes (OLEDs) were investigated and compared. To reveal the electroluminescent (EL) processes in these devices, the AC voltage and frequency dependence of the EL intensity and capacitive current were studied in the time domain with a focus on phase difference analysis. It was found that the voltage-dependent transit time and frequency-dependent carrier distribution were important for the AC-driven performance of the double-injection OLEDs. In contrast, although the double-insulated OLEDs shared some similarities with the double-injection OLEDs, they had some unique characteristics, which were the absence of resistive current and phase shift of EL profiles. It was revealed that the EL in the double-insulated OLEDs was driven by the displacement current generated by the ionization of the doped layers, which, however, formed space charge regions and undermined the EL emission. The space charge redistributed the electric field across the devices after the initiation of EL, making the EL maintain for a limited time interval. This effect was significant under low frequency and high AC voltage. Comparing the phase difference between both devices, it was indicated that the space charge effect was responsible for the observed EL phase shift and the asymmetric EL profiles at low frequency and high AC voltage in the double-insulated OLEDs. The proposed model was also of help to understand the EL saturation phenomena with AC frequency and voltage in those devices.     

A novel fuzzy pain demand index derived from patient-controlled analgesia for postoperative pain

A multilayer hierarchical structure for an intelligent analysis system is described in this paper. Four levels (patients', measurement, Web-based, and interpreting) are used to collect massive amounts from clinical information and analyze it with both traditional and artificial intelligent methods. To support this, a novel fuzzy pain demand (FPD) index derived from the interval of each bolus of patient-controlled analgesia (PCA) is designed and documented in a large-scale clinical survey. The FPD index is modeled according to a fuzzy modeling algorithm to interpret the self-titration of the drug delivery. A total of 255 patients receiving intravenous PCA using morphine (1 mg/ml) tested this index by offline analysis from this system. We found the FPD index modeled from a fuzzy modeling algorithm to interpret the self-titration of the drug delivery can show the patients' dynamic demand and past efforts to overcome the postoperative pain. Moreover, it could become an online system to monitor patients' demand or intent to treat their pain so these factors could be entered into a patient's chart along with temperature, blood pressure, pulse, and respiration rates when medical practitioners check the patients.     

A novel, wideband, lithium niobate electrooptic modulator

A set of floating electrodes and a relatively thick buffer layer of low-dielectric constant is interspaced between the coplanar RF transmission line and the LiNbO₃ substrate containing the optical wave-guide structure. The composite structure is designed to feature a 50-Ω characteristic impedance, to have an effective dielectric constant equal to that of the optical wave for close velocity match, and to have a 3 dB bandwidth of 40 GHz. The purpose of the floating electrodes is to optimize the modulation sensitivity resulting in an improvement of about 6 dB. As a result, the RF power required for full modulation is lower than heretofore reported changing over the range from below 2 GHz to 20 GHz, from 44 mW to less than 70 mW. The close agreement between the theoretical and experimental values of the design parameters demonstrates the usefulness of the quasistatic assumption in the analysis of the composite structure     

Near infrared electroluminescence from Nd(TTA)3phen in solution-processed small molecule organic light-emitting diodes

We report on the near infrared electroluminescence properties of a Nd³⁺ complex with thenoyltrifluoroacetone and 1,10-phenantroline ligands in solution-processed organic light-emitting diodes. Spin-coated blends containing a 1,3-bis(9-carbazolyl)benzene host doped with the Nd³⁺ complex were found to exhibit a photoluminescence quantum yield of about 0.5%, regardless of the doping concentration level. Electroluminescent devices based on these small molecule blends showed the characteristic emission of Nd³⁺ at 890, 1060 and 1330 nm with an external quantum efficiency as high as 0.022%. These improved performances were mainly attributed to direct charge trapping and exciton formation on the near infrared emitter. Importantly, the efficiency roll-off at high current densities due to triplet-triplet exciton annihilation in the device containing 20 wt% of the complex was lower than what is typically observed in lanthanide complex-based electroluminescent devices. This is presumably due to the high triplet energy of the host material, which prevents guest-to-host energy-back transfer and thus host-guest triplet-triplet exciton annihilation.     

Highly efficient photovoltaic diode based organic ultraviolet photodetector and the strong electroluminescence resulting from pure exciplex emission

We demonstrate organic photovoltaic (PV) and ultraviolet (UV) photodetector devices using 1,3,5-tris(3-methylphenyl-phenylamino)-triphenyamine and 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene to function as the donor (D) and the acceptor (A), respectively. Two types of structural devices, a planar heterojunction of layer-by-layer and a bulk heterojunction with a D/A blend layer are fabricated, respectively. Under UV-365 irradiation, the PHJ device offers a power conversion efficiency of ～10%, while the BHJ device behaves with a responsivity of 135 mA/W at ?4 V bias. The BHJ device can also obtain a high exciplex electroluminescence (EL). The dependencies of PV and EL performances on exciplex formation were also discussed.     

浅谈高比能量二次锂电池中金属锂负极材料

随着社会的高速发展以及能源问题的日益突显,各国均在寻找绿色环保的新能源.目前,金属锂是已知高比能量较好的电极材料,因此,以金属锂作为负极材料的二次锂电池成为科研领域的重点研究对象.本文着重阐述了金属锂作为二次锂电池负极存在的问题以及负极改性等思路,以供参考.     

Color switching behaviors of organic bistable light-emitting devices fabricated utilizing an aluminum-nanoparticle-embedded tris(8-hydroxyquinoline)aluminum layer and double emitting layers

Organic bistable light-emitting devices (OBLEDs) with an aluminum (Al)-nanoparticle-embedded tris(8-hydroxyquinoline)aluminum (Alq₃) layer and double emitting layers (EMLs) were fabricated to investigate their color switching behaviors. Scanning electron microscopy images showed that Al nanoparticles were formed on the Alq₃ layer. The Al nanoparticles in the Alq₃ layer improved the storage margin of the organic bistable devices (OBDs), and the double EMLs changed the emission color of the organic light-emitting devices (OLEDs) according to the variations of the ON and the OFF states of the OBDs. The variations of the ON and the OFF states of the OBDs could be clearly distinguished by the color switching of the OLED. The luminances of the OBLEDs with double EMLs in the ON and the OFF states were 641.80 and 22.25 cd/m², respectively, and their CIE coordinates at 20 V were (0.42, 0.46) and (0.51, 0.47), respectively, which corresponded to the ON and the OFF states of the OBLEDs.     

A novel all-plastic diode based upon pure polyaniline material

All-plastic electronic devices have developed increasingly nowadays and a trend to use them replacing the conventionally Si-based inorganic semiconductor devices is becoming attractive. Here, we developed a new and simple method to fabricate a single-component all-polymer diode based on a conducting polymer, polyaniline (PANI), using different manners to form films on two ends of a transparency with an obviously divided boundary between them. The different doping degree is considered to induce this rectification.     

A novel Z-source boost derived hybrid converter for PV applications

Analog Integrated Circuits and Signal Processing - This paper proposes a novel Z-source boost derived hybrid converter (ZSBDHC) that produces high gain dual output from a single DC input, which is...